Devices that are part of a security system for a premises are used to detect motion of doors, windows, and the like. A backplate of the device is mounted to the door or window, and the head unit of the device is correspondingly mounted to the backplate. Typically, the device has a simple switch to detect detachment of the head unit from the corresponding backplate. The position of the switch is used to detect tampering of the device when the head unit is dislodged from the backplate. However, tamper signals output from the device based on the switch position typically may generate false positives, which are frequently related to mechanical or electrical connectivity issues with the switch or with the mounting of the head unit to the backplate. This results in false tamper notifications in the security system.